package com.ujs.utils;

import java.util.List;
 
// 分页工具类
public class PageUtil<T> {

        private List<T> list;// 对象记录结果集
        private int total = 0;// 总记录数
        private int limit = 20;// 每页显示记录数

        private int pages = 1;// 总页数

        private int pageNumber = 1;// 当前页

        private boolean isFirstPage = false;// 是否为第一页

        private boolean isLastPage = false;// 是否为最后一页

        private boolean hasPreviousPage = false;// 是否有前一页

        private boolean hasNextPage = false;// 是否有下一页

        private int navigatePages = 8;// 导航页码数

        private int[] navigatePageNumbers;// 所有导航页号

        private int lastPage = 0 ;// 尾页

        private int firstPage = 1 ;// 首页

        private int prePage = 0;// 上一页

        private int nextPage = 0; // 下一页
 
 
        public PageUtil(int pageNumber, int limit, List<T> list) {
            init(list, pageNumber, limit);
        }
 
        private void init(List<T> list, int pageNumber, int limit){
            //设置基本参数
            this.list = list;
            this.total = list.size();
            this.limit = limit;
            this.pages = (this.total-1)/this.limit+1;
            this.lastPage = pages;
            this.firstPage = 1;
            this.prePage = pageNumber-1;
            this.nextPage = pageNumber+1;
            //根据输入可能错误的当前号码进行自动纠正
            if(pageNumber<1){
                this.pageNumber=1;
            }else if(pageNumber>this.pages){
                this.pageNumber=this.pages;
            }else{
                this.pageNumber=pageNumber;
            }
 
            //基本参数设定之后进行导航页面的计算
            calcNavigatePageNumbers();
 
            //以及页面边界的判定
            judgePageBoudary();
        }
 
        /**
         * 计算导航页
         */
        private void calcNavigatePageNumbers(){
            //当总页数小于或等于导航页码数时
            if(pages<=navigatePages){
                navigatePageNumbers=new int[pages];
                for(int i=0;i<pages;i++){
                    navigatePageNumbers[i]=i+1;
                }
            }else{ //当总页数大于导航页码数时
                navigatePageNumbers=new int[navigatePages];
                int startNum=pageNumber-navigatePages/2;
                int endNum=pageNumber+navigatePages/2;
 
                if(startNum<1){
                    startNum=1;
                    //(最前navPageCount页
                    for(int i=0;i<navigatePages;i++){
                        navigatePageNumbers[i]=startNum++;
                    }
                }else if(endNum>pages){
                    endNum=pages;
                    //最后navPageCount页
                    for(int i=navigatePages-1;i>=0;i--){
                        navigatePageNumbers[i]=endNum--;
                    }
                }else{
                    //所有中间页
                    for(int i=0;i<navigatePages;i++){
                        navigatePageNumbers[i]=startNum++;
                    }
                }
            }
        }
 
        /**
         * 判定页面边界
         */
        private void judgePageBoudary(){
            isFirstPage = pageNumber == 1;
            isLastPage = pageNumber == pages && pageNumber!=1;
            hasPreviousPage = pageNumber!=1;
            hasNextPage = pageNumber!=pages;
        }
 
        /**
         * 得到当前页的内容
         * @return {List}
         */
        public List<T> getList() {
 
            int endIndex = total;
            if(pageNumber*limit <= total){
                endIndex = pageNumber*limit;
            }
 
            List<T> pagelist = list.subList((pageNumber-1)*limit, endIndex);
          return pagelist;
        }
 
    public int getLastPage() {
        return lastPage;
    }
 
    public void setLastPage(int lastPage) {
        this.lastPage = lastPage;
    }
 
    public int getFirstPage() {
        return firstPage;
    }
 
    public void setFirstPage(int firstPage) {
        this.firstPage = firstPage;
    }
 
    public int getPrePage() {
        return prePage;
    }
 
    public void setPrePage(int prePage) {
        this.prePage = prePage;
    }
 
    public int getNextPage() {
        return nextPage;
    }
 
    public void setNextPage(int nextPage) {
        this.nextPage = nextPage;
    }
 
        /**
         * 得到记录总数
         * @return {int}
         */
        public int getTotal() {
            return total;
        }
 
        /**
         * 得到每页显示多少条记录
         * @return {int}
         */
        public int getLimit() {
            return limit;
        }
 
        /**
         * 得到页面总数
         * @return {int}
         */
        public int getPages() {
            return pages;
        }
 
        /**
         * 得到当前页号
         * @return {int}
         */
        public int getPageNumber() {
            return pageNumber;
        }
 
 
        /**
         * 得到所有导航页号
         * @return {int[]}
         */
        public int[] getNavigatePageNumbers() {
            return navigatePageNumbers;
        }
 
        public boolean isFirstPage() {
            return isFirstPage;
        }
 
        public boolean isLastPage() {
            return isLastPage;
        }
 
        public boolean hasPreviousPage() {
            return hasPreviousPage;
        }
 
        public boolean hasNextPage() {
            return hasNextPage;
        }
 
       
    }